1. Field of the Invention
The present invention relates to mast assemblies of drilling rigs. More particularly, the present invention the relates to “boot strap” types of rig assemblies. More particularly, the present invention relates to the formation of mast assemblies in which sections of the mast assembly are installed vertically in end-to-end relation.
2. Description of Related Art
Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Conventional oil drilling in exploration in major land drilling operations require the rapid deployment, assembly and disassembly of drilling structures. Consequently, the transportability of components and the speed at which components can be assembled with a minimum amount of auxiliary equipment are paramount concerns. A transportable oil drilling rig typically includes, for example, a support base, a mast, pipe sections, and a drill floor. Often times, however, auxiliary equipment, such as cranes, are required to facilitate the set-up and take-down of large components such as the base, the drill floor, the pipe racking boards, and the mast. This has the effect of increasing operational costs.
Drilling sites are often located in remote areas requiring truck transportation of the components of the rig accompanied by equipment used to assemble the rig. Further complicating the rig assembly process is the persistent need to change locations once a hole is sunk and it is determined whether the site will be sufficiently productive to merit a pumping installation, whether the site will be unproductive, or whether a more ideal location exists to sink a hole. Typically, site changes can occur once every several months and, in response, prior art systems have attempted to increase the degree of mobility of rig components.
Since the variable costs associated with leased support equipment, such as the cranes and the like, are calculated on the per hour or day basis, expediting the takedown, transport and set-up operations is crucial for minimizing equipment leasing costs. Typical takedown and setup time is in the order of days. With equipment leasing costs ranging from several hundred dollars per day or more, many thousands of dollars in cost may be incurred for each end of a setup and takedown operation. For larger or more complex rigs, the cost may be even higher. In general, prior art drilling rigs are geared for facilitating rapid setup, takedown and transport but still require external cranes, external winches, and the like which are most often leased so as to increase overall expense.
In order to move a large drilling rig, including all of its equipment, from one well bore to another, it has been necessary to disassemble or “rig down” the drilling structure. This requires disconnecting all ancillary services and laying down the mast from a vertical to a horizontal position, moving the drilling structure to an alternative well bore, then reassembling the entire drill structure and reconnecting all ancillary services.
The drilling site and drilling rig may be configured in various known ways and may include various equipment. The drilling rig will often have an upstanding mast having an open face connected to the floor of the drilling rig. The mast may extend vertically forty to fifty meters or more and support a crown assembly at the top. The mast and floor are located above and are connected to an elongated substructure.
In the past, systems have been employed whereby the known truncated pyramid-shaped drilling rigs are positioned above the rig floor. In normal operation, these types of mast assemblies are assembled in a generally horizontal orientation. The various components of this type of mast assembly are supported, during assembly, by an item known as a “headache rack”. As such, when each section of the mast assembly is assembled, the headache rack can be moved to the end that remains away from the rig. When the entire mast assembly has been completed, suitable cables, lines, cranes, and other equipment are required in order to pivot the mast assembly from the horizontal to the vertical position. The elevation of the rig in this manner can pose severe dangers to the safety and welfare of the workers in the area of the rig.
In the past, various patents have issued relating to the assembly of drilling rigs. For example, U.S. Pat. No. 3,996,754, issued on Dec. 14, 1976 to E. L. Lowery, shows a mobile marine drilling unit. This mobile drilling unit has a floatable base, a floatable platform, and a vertical support leg attached to said base and extending upwardly through a well provided therefor in the platform. The base and a major portion of the leg are submergible in a body of water for support on the floor thereof. The support leg and platform are provided with elevating mechanisms for elevating the platform above the body of water on the leg.
U.S. Pat. No. 4,569,168, issued on Feb. 11, 1986 to McGovney et al., provides a self-elevating substructure for a portable oil derrick. This substructure has a base frame, a top frame and an intermediate bifurcated support frame consisting of a pair of horizontally extending traveling frames. A linkage network of swingable leg members intercouples the base, traveling and top frames for movement in parallelism between collapsed and elevated conditions of the substructure. In the collapsed mode, the frame members are positioned in an adjacent relationship for presenting a low profile to a flatbed truck which allows a portable oil rig to be easily shifted onto the top frame and into alignment with the oil wellhead therebelow. A block-and-tackle assembly operably engages the traveling frames and is coupled to the derrick hook carried by the traveling block. Upon completion of the latter, the swingably mounted traveling frames move towards each other causing an elevation of the top frame so as to present a working space between the elevated oil derrick and oil wellhead. The traveling frames are locked one to the other to maintain the top frame at its elevated position with collapsible end sway braces precluding lateral shifting of the top frame and oil rig thereon.
U.S. Pat. No. 4,899,832, issued on Feb. 13, 1990 to R. C. Bierscheid, Jr., shows an automated well drilling apparatus that is transportable in modular units to a well site. The units can be rapidly assembled into an integrated operational assembly. The apparatus includes a drilling unit and two raising units that are locked to the respective opposite sides thereof. After base structures on the raising units are lowered to the ground to provide a support, the towers of the raising units and the mast of the drilling unit are simultaneously elevated to the vertical. The same raising units are then employed to erect pipe supply frames that are connected to the front of each tower.
U.S. Pat. No. 6,634,436, issued on Oct. 21, 2003 to V. Desai, provides a mobile land drilling apparatus and method. A mobile telescoping substructure box includes at least one axle and carriage assembly
A lifting means selectively supports the mobile telescoping substructure box unit in a raised position and lowered position with respect to the ground. An extension cylinder further extends the mobile telescoping substructure box unit. A stationary frame member and a telescoping frame member comprising the mobile telescoping substructure box unit have a plurality of cables attached thereto for supporting the telescoping frame member when extended.
U.S. Pat. No. 7,306,055, issued Dec. 11, 2007 to R. M. Barnes, describes a method for installing a mobile drilling rig at a drilling site. This method entails transporting the mobile drilling rig to the drilling site. The mobile drilling rig is made of three sections. The two substructures are placed parallel to one another at the drilling site. The mast section is connected to the mast starting sections located on each substructure. Raising cylinders on the substructures engage the mast and raise the mast into a substantially vertical orientation. In this position, the mast is locked in place. The raising cylinders are retracted and then re-extended into a drill floor raising position.
U.S. Pat. No. 7,357,616, issued on Apr. 15, 2008 to Andrews et al., provides a method and apparatus for transporting an oil rig. The oil rig is capable of being at least partially disassembled to form at least two portions. The top portion of the oil rig can be loaded onto a trailer for transport separate from a bottom portion. The trailer includes a bottom frame, a top frame, a structure operably associated with the bottom and top frames for moving the top and bottom frames from and towards one another. There is a moving means attached to at least the bottom frame to allow the trailer to be moved along the support surface.
It is an object of the present invention to provide a method and apparatus for forming a mast assembly that avoids the use of cranes and cables in achieving proper assembly over the well.
It is another object of the present invention to provide a method and apparatus for forming a mast assembly that enhances the structural integrity of the mast assembly.
It is another object of the present invention to provide a method and apparatus for forming a mast assembly that allow the formation of mast assemblies having an elevation of 160 feet or more.
It is still another object of the present invention to provide a method and apparatus for forming a mast assembly which allows the mast assembly to be assembled in compression throughout the assembly process.
It is still another object of the present invention to provide a method and apparatus for forming a mast assembly that enhances safety conditions for workers in the area of the drilling rig.
It is still another object of the present invention to provide a method and apparatus for forming a mast assembly which minimizes the amount of material required for the formation of the mast assembly.
It is still another object of the present invention to provide a method and apparatus for forming a mast assembly which enhances the ability to efficiently and effectively assemble the mast assembly.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.